Reducing drag on a mobile body

ABSTRACT

A vortex ring generator adapted to be associated with a body subjected to fluid flow, the vortex ring generator being adapted to produce a fluid flow in the form of a vortex ring with the fluid flow moving over the body from the vortex ring generator.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation and claims the priority benefit ofU.S. patent application Ser. No. 11/980,168 filed Oct. 29, 2007, andentitled “Vortex Ring Generator,” which is a continuation of U.S. patentapplication Ser. No. 10/884,032 filed Jul. 2, 2004 and entitled “VortexRing Generator,” which is a continuation and claims the priority benefitof Patent Cooperation Treaty application number PCT/AU03/00003 filedJan. 3, 2003, which in turn claims the priority benefit of Australianpatent application number PR 9827 filed Jan. 3, 2002 and Australianpatent application number PS 1352 filed Mar. 26, 2002. The disclosure ofthese applications is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of fluid mechanics and moreparticularly to the flow of a fluid relative to a body. Moreparticularly, this invention seeks to reduce drag on a body or fuselageduring relative movement of the body with respect to a fluid.

The invention is described herein by reference to its use in respect toany mobile body or fuselage, such as, including, but not limited to,projectiles, missiles, torpedoes, submarines and aircraft. However, theinvention is not restricted to mobile fuselages, but may also be used toreduce drag on stationary bodies such as buildings, bridge pilings, andfixed obstacles in watercourses, airways or other fluid flow fields.Such applications are intended to be within the scope of the inventionalthough not specifically described herein.

2. Background Art

The greatest obstacle to obtaining optimum efficiency in streamlining afuselage is surface friction. This can be in several forms but typicallyis one of or a combination of boundary layer drag, skin friction,viscosity, surface tension, cavitation and turbulence.

Existing technologies seek to reduce this drag and optimise the energyefficiency of a moving body or fuselage by altering its surface to be assmooth as possible with the least possible protuberances oralternatively to roughen the smooth surface or to give it a ripplingsurface similar to that of a shark, dolphin or golf ball. The objectiveis to minimise the effects of drag from fluids flowing past. Anotherattempt to cut drag has included the fitting of small vortex generatorsto wings and other parts of the fuselage. A further attempt has been tofit a spike-like protuberance extending forwardly in the direction oftravel of the fuselage through the fluid.

In general, it has been an objective of these attempts to maintainstraight, laminar flow over the body of the fuselage, and to suppressseparation or turbulence as far as is possible. Alternatively, throughthe use of dimpled or roughen surfaces and vortex generators, theobjective has been to create myriad eddies in close proximity to thefuselage surface to break up the boundary layer. Essentially, all theseapproaches are designed to assist fluids slide past the body with aminimum of friction.

SUMMARY OF THE INVENTION

A first embodiment of the claimed invention provides for a vortex ringgenerating system inclusive of a body and spiraled surfaces affixed tothe body. The body propels fluid from a forward portion to a rearportion when in motion. The spiraled surfaces are alternately concaveand convex surfaces. A portion of each surface conforms substantially toa logarithmic spiral, wherein the radius of the logarithmic spiralmeasured at equiangular radii unfolds at a constant order of growth. Thespiraled surfaces commence near the forward portion of the body andterminate near a rear portion of the body. The surfaces generate avortex ring surrounding the body as the body propels the fluid from theforward portion toward the rear portion.

A second embodiment of the claim invention provides for a vortex ringgenerator that includes a mobile body and vanes extending outward fromthe body, which includes a nose and a tail. The vanes commence near thenose and end near the tail. The vanes define a spiral path around thebody and are alternately configured as concave and convex surfaces. Aportion of each surface of the plurality of vanes conforms substantiallyto a logarithmic spiral, wherein the radius of the logarithmic spiralmeasured at equiangular radii unfolds at a constant order of growth. Thevanes generate a vortex ring with respect to a fluid incident to themobile body and propel the fluid from the nose of the body toward thetail of the body.

A third claimed embodiment of the present invention includes a mobilebody configured to reduce drag in a flowing fluid. The mobile bodyincludes an axis aligned with a direction of the flowing fluid relativeto the mobile body. The mobile body includes a nose and tail. A vortexring generator coupled to the body includes a helical vane disposedaround a central axis aligned with the axis of the body, the vaneextending from the nose to the tail of the body. The vane includesalternately configured concave and convex surfaces. A portion of thehelical vane conforms to a logarithmic curve, wherein the radius of thelogarithmic curve measured at equiangular radii unfolds at a constantorder of growth. The vortex ring generator induces a vortex ring aroundthe body whereby the drag of a flowing fluid against the body is reducedas the body propels the flowing fluid along the axis aligned with adirection of the flowing fluid relative to the body.

A method for reducing drag on a mobile body in a fluid is provided andclaimed. The method includes configuring the mobile body with spiraledsurfaces affixed to the mobile body. The spiraled surfaces arealternately configured as concave and convex surfaces. A portion of eachof the spiraled surfaces conforms substantially to a logarithmic spiral,wherein the radius of the logarithmic spiral measured at equiangularradii unfolds at a constant order of growth. The spiraled surfacescommence near the forward portion of the mobile body and terminate nearthe rear portion of the mobile body. The spiraled surfaces induce theformation of a vortex ring surrounding the mobile body. The mobile bodyis then subject to a fluid. Vortex rings are then generated to reducedrag on the mobile body as the fluid flows over the mobile body, thefluid being propelled by the mobile body.

A further claimed method is for generating a vortex ring to reduce dragon a mobile body in a fluid. The body is configuring with spiraledsurfaces affixed to the body. The spiraled surfaces are alternatelyconfigured as concave and convex surfaces. A portion of each of thespiraled surfaces conforms substantially to a logarithmic spiral,wherein the radius of the logarithmic spiral measured at equiangularradii unfolds at a constant order of growth. The spiraled surfacescommence near the forward portion of the body and terminating near therear portion of the body. The body is subjected to a fluid and rotated,which propels the fluid from the forward portion of the body toward therear portion of the body. The rotation of the body generates a vortexring. As a result, drag is reduced on the body as the fluid flows fromthe forward portion of the body toward the rear portion of the body.

In a final claimed embodiment, a vortex ring generator comprising a bodyand a surface is provided. The body is subjected to relativetranslational movement with a fluid along a line of movement. The bodyhas no substantial rotational movement about an axis parallel to theline of movement. The surface is three dimensional and spiraling in formand coupled to the body. A portion of the surface conforms to alogarithmic curve. The surface generates a vortex ring in the fluid inrelation to the body, the vortex ring having an axis substantiallyparallel to the line of movement.

BRIEF DESCRIPTION OF THE DRAWINGS

The description is made with reference to the accompanying drawings, ofwhich:

FIG. 1 illustrates the form of the Golden Section;

FIG. 2 is a side elevation of a vortex ring generator according to thefirst embodiment;

FIG. 3 is a front end view of a vortex ring generator according to thefirst embodiment;

FIG. 4 is a rear end view of a vortex ring generator according to thefirst embodiment;

FIG. 5 is a side elevation of a vortex ring generator mounted to a bodyaccording to the first embodiment;

FIG. 6 is a side elevation of a vortex ring generator applied to a bodyaccording to the second embodiment;

FIG. 7 is a front end view of a vortex ring generator applied to a bodyaccording to the second embodiment;

FIG. 8 is a front end view of a vortex ring generator applied to a bodyaccording to the third embodiment;

FIG. 9 is a side elevation of a vortex ring generator applied to a bodyaccording to a third embodiment;

FIG. 10 is a diagrammatic representation of the flow of vortex ringsaround a body having a vortex ring generator according to the first andthird embodiments;

FIG. 11 is a diagrammatic representation of the flow of vortex ringsaround a body having a vortex ring generator according to the secondembodiment;

FIG. 12 is a diagrammatic representation of the generation of a vortexrings around a vortex ring generator according to the first embodiment.

DETAILED DESCRIPTION

Each of the embodiments comprises a vortex ring generator associatedwith a body and adapted to generate a vortex ring in the fluid movingrelative to the body. In each embodiment, the vortex ring generatorcomprises a fluid pathway having an active surface adapted to influencethe flow of the fluid to form the vortex rings flowing past the body.

As stated previously all fluids when moving under the influence of thenatural forces of Nature, tend to move in spirals or vortices. Thesespirals or vortices generally comply with a mathematical progressionknown as the Golden Ratio or a Fibonacci like Progression.

The greater percentage of the surfaces of the active surfaces of each ofthe embodiments described herein are generally designed in the greaterpart, in accordance with the Golden Section or Ratio and therefore it isa characteristic of each of the embodiments that the active surfaces areof a spiralling configuration and which conform at least in greater partto the characteristics of the Golden Section or Ratio. Thecharacteristics of the Golden Section are illustrated in FIG. 1 whichillustrates the unfolding of the spiral curve according to the GoldenSection or Ratio. As the spiral unfolds the order of growth of theradius of the curve which is measured at equiangular radii (eg E, F, G,H, I and J) is constant. This can be illustrated from the triangularrepresentation of each radius between each sequence which corresponds tothe formula of a:b=b:a+b which conforms to the ratio of 1:0.618approximately and which is consistent through out the curve.

A characteristic of the embodiments is that not only do the X and Y axisconform to Golden Section geometry, but also the Z axis or depthconforms, that is the vanes conform to the Golden Section in threedimensions.

It is an objective of the embodiments to duplicate the lines ofvorticity found in a ring vortex. To that end, the active surfacesexpand or contract logarithmically in any direction in an equiangular,Golden Section spiral. If any two points are taken on the surface ofthese active surfaces they will bear a ratio to each other ofapproximately 1:0.618. The active surfaces can be any length or numberof rotations. They are specifically designed to match the internal,streamlined flow lines of vorticity of a vortex.

In the first embodiment, and as shown in FIGS. 2 to 5, the vortex ringgenerator (11) comprises a set of vanes located at the nose (13) of abody (12). In this specification, the term nose is used to identify theportion of the body which is intended to face the direction from whichthe relative flow of fluid is approaching the body.

The vortex ring generator (11) is adapted to generate a vortex ring byinfluencing the flow of the fluid relative to the body in a way whichproduces a vortex ring. The vanes comprising the vortex ring generatorextend forwardly from the nose of the body and have the configuration ofa whorl. Each of the vanes are formed with an internal reactive face(14) which is of a concave configuration and which has a threedimensional curvature of a concave nature whereby the curvature in eachdirection is in accordance with a logarithmic curve conforming to theGolden Section. As a result, the vanes (11) jointly define a generallyconcave internal face of the vortex ring generator.

In addition, each vane has a remote reactive face (15) which is remotefrom the internal reactive face (14) and which also has a threedimensional curvature of a convex nature whereby the curvature in eachdimension conforms with a logarithmic curve according to the GoldenSection, and whereby the curvature in each dimension is of the same formas the curvature of the internal reactive face (14) in each dimension.As a result, the remote reactive faces (15) jointly define a generallyconvex surface of the vanes.

In an adaptation of the first embodiment, the vortex ring generator isnot fixedly mounted to the nose but rather is adapted to rotatecoaxially with the axis of the body. In addition, the generator may bedriven mechanically to rotate thereby providing propulsion to the bodywhilst simultaneously generating vortex rings.

In the second embodiment, as shown in FIGS. 6 and 7, the vortex ringgenerator comprises a set one or more grooves or flutes (21) in thesurface of the body, commencing at or near the nose (23) of the body(22) and ending at or near the tail (24) of the body. The paths of thegrooves or flutes along the body spiral around the body in a mannerdesigned to conform to the Golden Ratio.

In the third embodiment, as shown in FIGS. 8 and 9, the vortex ringgenerator comprises a set one or more vanes (31) extending outwardlyfrom the surface of the body, commencing at or near the nose (33) of thebody (32) and ending at or near the tail (34) of the body. The paths ofthe vanes along the body spiral around the body in a manner designed toconform to the Golden Ratio.

The body in each of the above embodiments is ideally designed inaccordance with a logarithmic, equiangular, Phi spiral. Its shape isoptimally compatible with Phi vortex geometry, which is common to allvortices. In other words the body occupies that space which is seen inthe cavitation tube of a visible vortex.

As depicted in FIG. 11, the body, 13, is accommodated within the core ofthe vortex, 16. The nose of the body, by use of embodiment one, two orthree above exactly fits the geometry of a ring vortex. The body may becone-shaped with a hollow centre allowing fluid incoming to the vortexring to travel through its core.

FIGS. 10 and 11 illustrate the creation of ring vortices, 16, whichtravel/roll along the body.

In operation, with relative movement between the fluid and the body, thefluid is engaged by the active surfaces 11, 21 or 31 and commencesrotating in a logarithmic vortical fashion. As the fluid engages theactive surfaces, the rotary motion creates a low-pressure area at thebase of the vortex generator (the interface between the generator andthe nose of the body). This reduces the boundary layer drag of the body.A ring and/or potential vortex is established. As can be seen in FIG.10, the ring vortex rolls up the boundary layer, like ball bearings,along the body walls. In many applications vortex rings will shed andgive rise to a stream of shed vortex rings. The wake left behind thebody is in the shape of vortex rings.

FIG. 12 illustrates the vortex ring generator, 11 of the firstembodiment creating a ring vortex, 16. To do so, there must be relativemotion between the vortex ring generator, 11, and the fluid.

This motion can be created by rotation of the vortex ring generator; themovement of fluid past a stationary vortex ring generator, or thepropulsion of the body and vortex ring generator through the fluid.

It should be appreciated that the scope of the present invention neednot be limited to the particular scope described above.

Throughout the specification, unless the context requires otherwise, theword “comprise” or variations such as “comprises” or “comprising”, willbe understood to imply the inclusion of a stated integer or group ofintegers but not the exclusion of any other integer or group ofintegers.

1. A method of reducing drag on a mobile body in a fluid, comprising:subjecting a mobile body to the fluid, wherein the mobile body includesa plurality of affixed spiraled surfaces each conforming substantiallyto a logarithmic spiral, wherein the radius of the logarithmic spiralmeasured at equiangular radii unfolds at a constant order of growth, theplurality of spiraled surfaces commencing proximate the forward portionof the mobile body and terminating proximate the rear portion of themobile body, the plurality of spiraled surfaces inducing the formationof a vortex ring surrounding the mobile body; and introducing a fluidflow over the mobile body from the forward portion of the mobile bodytoward the rear portion of the mobile body thereby generating a vortexring to reduce drag on the mobile body.
 2. (canceled)
 3. The method ofclaim 1, wherein each of the plurality of spiraled surfaces does notrotate relative to the mobile body.
 4. The method of claim 1, whereineach of the plurality of spiraled surfaces extends without interruptionfrom the forward portion of the body to the rear portion of the body. 5.The method of claim 1, wherein at least one of the plurality of spiraledsurfaces includes a vane, at least a portion of the vane being incontact with the fluid.
 6. The method of claim 5, wherein the vaneincludes a surface area conforming substantially to a logarithmic curve,wherein the radius of the logarithmic curve measured at equiangularradii unfolds at a constant order of growth.
 7. The method of claim 5,wherein the vane includes an internal reactive face and a remotereactive face.
 8. The method of claim 1, wherein the plurality ofspiraled surfaces forms a path around and along the body.
 9. The methodof claim 8, wherein the path of the plurality of spiraled surfacesconforms substantially to a logarithmic spiral, wherein the radius ofthe logarithmic spiral measured at equiangular radii unfolds at aconstant order of growth.
 10. The method of claim 1, wherein the mobilebody is conical with a hollow center.
 11. A method of generating avortex ring to reduce drag on a mobile body in a fluid, comprising:subjecting a mobile body to the fluid, wherein the mobile body includesa plurality of affixed spiraled surfaces each conforming substantiallyto a logarithmic spiral, wherein the radius of the logarithmic spiralmeasured at equiangular radii unfolds at a constant order of growth, theplurality of spiraled surfaces commencing proximate the forward portionof the mobile body and terminating proximate the rear portion of themobile body; and introducing a fluid flow over the mobile body from theforward portion of the mobile body toward the rear portion of the bodywhile rotating the mobile body, the rotation of the body generating avortex ring to reduce drag on the mobile body.
 12. The method of claim11, wherein each of the plurality of spiraled surfaces does not rotaterelative to the mobile body.
 13. The method of claim 11, wherein each ofthe plurality of spiraled surfaces extends without interruption from theforward portion of the body to the rear portion of the body.
 14. Themethod of claim 11, wherein at least one of the plurality of spiraledsurfaces includes a vane, at least a portion of the vane being incontact with the fluid.
 15. The method of claim 14, wherein the vaneincludes a surface area conforming substantially to a logarithmic curve,wherein the radius of the logarithmic curve measured at equiangularradii unfolds at a constant order of growth.
 16. The method of claim 14,wherein the vane includes an internal reactive face and a remotereactive face.
 17. The method of claim 11, wherein the plurality ofspiraled surfaces forms a path around and along the body.
 18. The methodof claim 17, wherein the path of the plurality of spiraled surfacesconforms substantially to a logarithmic spiral, wherein the radius ofthe logarithmic spiral measured at equiangular radii unfolds at aconstant order of growth.
 19. The method of claim 11, wherein the mobilebody is conical with a hollow center.